1. Field of the Invention
The invention pertains to additional damping for a passive magnetic bearing by mounting the magnetic elements and/or assembly on a resilient material, such as an elastomer or woven metal pad, having both stiffness and damping properties.
2. Description of the Prior Art
Passive magnetic bearings for rotating machines generally possess very small amounts of vibrational damping. Therefore, in the machinery systems which include rotors, support on these bearings can be expected likewise to show very light damping. This condition is manifested by very large vibratory amplitudes as rotors traverse their critical speeds, great sensitivity to unbalanced conditions and poor resistance to instability. One method for increasing the damping in a passive magnetic bearing is to introduce a non-magnetic, electrically conducting material into the rotor/stator gap, creating increased hysteresis losses. However, losses due to hysteresis are insufficient to generate the degree of damping required in many rotating machinery applications.